Apparatus for accomplishing mold movement in continuous casting machines



Nov. 3, 1964 H. BIERI 3,154,315

APPARATUS FOR ACCOMPLISHING MOLD MOVEMENT IN CONTINUOUS CASTING MACHINES Filed Nov. 22, 1961 INVENTOR. HANS BIERI wa -L M ATTORNEYJ United States Patent APPARATUS ESE ACQGMPLIdl-HNG MQLD 4T 1N CQNTEQUO'US CASTING MAiIHTNES Hans Biera', Uster, Switzerland, assignor to Erin Allan @lsson, Kusnaeht, Switzerland Filed Nov. 22, 1961,592'. No. 354,283 fillaims priority, application Sweden Dec. 13, 169 8 Claims. (Ci. re-zs) In continuous casting machines of the type wherein the casting passes through an open-ended mold which accompanies the movement of the casting or ingot over a certain distance, various types of mold movements are utilized. In some cases the mold is forced to accompany the continuously withdrawn casting over a shortdistance, e.g. 3O nuns, to be returned thereafter to an upper reversing position. In another method, the mold is supported on resilient means wmch yield and permit the mold to accompany the casting if the friction between the casting and the mold wall exceeds the resilient force but then return the mold as the friction is reduced. In a third method, the mold is pushed intermittently up toward an upper reversing position to be moved therefrom by gravity (or, in horizontal casting, by means of a counterweight or the like) downwards (in the casting direction), the force acting in the casting direction being so bflanced, however, that the friction'betwee-n the casting and the mold wall inhibits such movement, thereby necessitating a synchronous movement between casting and mold.

The methods of effecting mold movement are many and may be based on a mechanical drive by means of cam discs or on hydraulic or pneumatic drive by means of cylinder piston devices. Examples of some conventional methods and apparatuses for accomplishing reciprocating mold movements are disclosed in US. patents as follows: 2,135,183, issued to Junghans Nov. 1, 1938; 2,871,534, issued to Wieland Feb. 3, 1 959; and 2,947,075, issued to Schneckenburger et al. Aug. 2, 1960.

The object of the present invention is to provide means in continuous casting machines for achieving mold movement by the aid of one or more cylinders, said means being such as to permit the desired principle of mold movement to be freely chosen. Thus, the means shall be such that it can be used for a mold movement at a frictioi controhed speed, regardless of whether the friction is intended to enable the mold to 'be entrained in the casting direction against a resilient force acting thereupon, or the friction'is intended to brake the mold in the'otherwise more rapid movement the casting direction. The means shall also be capable of .being utilized fora purely positive control, if desired influenced'by'the casting speed.

This and other objects .of this invention are achieved by an apparatus in which the mold movement in the casting direction is achieved by means of the force acting in the casting direction, e.g. the whole or part of the weight of the mold and movable cylinder parts or this weight -in conjunction with a second force acting in the same direction, the displacement of the pressure fluid introduced into the cylinder or cylinders to affect mold movement in the opposite direction and thereby the velocity or" movement of the mold in the casting direction being determined by an outflow valve actuated by the pressure fluid.

This and other features characteristic of this invention will be explained more in detail below with reference to the drawing which illustrates an embodiment thereof shown diagrammatically and in cross-section.

Referring to the drawing, the mold 1 is carried by an annular piston 2 which cooperates with a corresponding annular cylinder 3 which in a manner not shown in "ice the drawing is attached to the frame of the continuous casting machine. The lower portion of the cylinder 3 communicates through a conduit 4 with a chamber 5 in a housing '6 which accommodates the members required for control or adjustment of the mold movement. The chamber '5 communicates via a valve 7 with a cylinder 3 wherein there is provided a piston 9 the piston rod it) of which extends through the cylinder bottom, .a spring 11 being interposed between the lower end of the piston rod and the cylinder bottom, said spring tending to move the piston 9 towards the lower position shown in the drawing. The cylinder 8 also communicatesvia a valve 12 witha reservoir 13 formed in the housing 6 to accommodate the necessary operating fluid, e.g. oil. To clean the oil supplied from the reservoir 13 to the cylinder 8 a strainer 14 is preferably provided. Between the chamber 5 and the reservoir 13 there is further provided a valve 15, through which oil can flow back to the reservoir 13 during the downward movement of the mold 1 and the annular piston 2. This valve 15 is acted upon by a spring 16 which is interposed between the top surface of the valve and a piston 18 provided in a further cylinder 17', said spring 16 biassing the valve toward its closing position, and also by .a second spring 39 which through a valve rod 2-? tends to move the valve to its open position. The spring force of the latter spring 19 is adjustable by means of an adjustment knob 21. The valve 12 is normally kept closed by the action of a relatively weak spring 22. To adjust the length of the opening stroke of the valve 7, there is a stop member 24 which is adjustable by a knob 23.

The space at the lower side of the piston 9 and the space at the upper side of the piston 18 communicate with a source of compressed air, such as .a compressed air container 25 througha conduit 26 and a conduit 27 respectively. in .each of said conduits there is provided an electrically actuated valve .23 and 29 respectively, by which said spaces at the lower sideof piston 9 andat the upper side of piston 13 are placed into communication either with the compressed air container 25 or with the atmosphere through outlet conduits 3i and 31 respectively. The valves are controlled by limit switches 32 and 33 which are adapted to be operated by the annular piston 2 in its two end positions.

In the case where the apparatus described is to be utilized so that the movement of the mold toward the lower end position is to .be braked by friction between the mold and the casting, the apparatus will function in the following manner, starting from the lower end .position of the mold, i.e. :the position shown in the drawing.

In this position, the mnular p ston 2 operates the limit switch 33, which delivers an impulse to the two valves 28 and 29 which put the compressed air container 25 in communication with the space below piston 9 and the space above piston 18, whereby an upward movement is imparted to the piston and the piston 13 keeps the valve 15 closed. On upward movement of the piston '9 the oil opens the valve 7 against the action or" a spring 34 acting thereupon, enters the chamber 5 and flows therefrom through the conduit 4 into the cylinder 3, whereby the annular piston 2 and thus the mold 1 move upwards. By adjustment of stop member 24 the opening stroke of valve '7 and thereby the speed at which the mold moves upwards can be varied as desired.

When the mold reaches the upper end position, the annular piston 2 actuates the second limit switch 32 which reverses the air valves 28 and 29 so that the space below the piston g and the space above the piston 18 are set in communication with the atmosphere through the conduits 3i and 31 respectively. Thereby the piston 9 moves downwards under the action of the spring 13. to

its lower position, and on account of the resulting reduction in pressure the valve 12 opens and fresh oil is aspirated into the cylinder from the reservoir 13.

The mold and the annular piston supporting the mold tend to move downwards by gravity and therefore tend to force the oil through the valve 15 back to the reservoir 13. a This is possible if the resultant resilient force of the two springs 16 and 19 acting on the valve 15 is less than the force generated by the weight of the mold and the piston minus the friction force existing between the casting and the mold. If this resultant spring force which is controllable by means of the knob 21 is adjusted so that almost the entire combined weight of the mold and the annular piston (minus the friction in gaskets and the like) is required to open the valve 15, the friction between the casting and the mold will determine the opening of the valve and consequently the velocity of the mold movement will be determined by said friction.; The length of the opening movement of the valve 15 is controllable by means of a stop 36 acting on the top surface of the piston 18 and adjustable by means of a knob 35, the opening movement of the valve being suitably adjusted so that the velocity of the movement of the mold corresponds to the desired velocity at the maximum casting speed occurring in the case that friction between the casting and the mold should fail to appear.

If the apparatus to be used for mold movement characterized by the friction between casting and mold causing the mold to be entrained in the casting direction, the resultant force of springs 16 and 19 acting on the valve 15 will be adjusted by means of knob 21 so that the combined weight of the mold and the annular piston (reduced by the friction in cylinder gaskets and the like) is not capable of exerting a suflicient pressure on the oil to open the Valve 15 without the application of an additional force, i.e. the friction force between casting and mold.

When the apparatus is to be used for a positive control, the rate of flow of the oil out of the cylinder is adjusted to a desired level in relation to the casting velocity (synchronous movement or a predetermined advance) by means of a separate valve or the valve 15. In the latter case, the knob 21 can suitably be replaced by'a lever or other suitable member controlled either directly from the lever for regulating the casting speed or from another pneumatic, hydraulic or electrical means which in its turn is controlled from a member responsive to the casting speed, e.g. the pinch rolls or their driving means.

As seen from the above, the invention provides a simple and inexpensive control means which also 'enables various movements of the mold to be chosen as desired to suit the casting of various materials and dimensions. To enable a horizontal displacement of the cylinder piston device and thereby a. horizontal movement of the mold 1 relative to the other parts of the machine to be achieved, which is desirable in many cases, the conduit 4 can be replaced by a flexible or bendable tube.

The invention is not restricted to the embodiment illustrated and described which can be varied in many ways within the scope of the invention. Thus, the invention also embraces the use of one or more cylinders of conventional type connected in parallel or in series.

tion wherein the movement of the mold in the casting direction is augmented by the force of at least a part of the weight of the mold, said means comprising a fluid pressure cylinder, a piston reciprocable in said cylinder and secured to said mold, a pressure fluid reservoir, duct means connecting said reservoir to one part of said cylinder at one side of said piston to permit flow of pressure fluid into and out of said cylinder for moving said piston and secured mold against and in the direction of casting respectively, an inflow valve and an outflow valve controlling said flow of pressure fluid into and out of said cylinder, and means for controlling operation of said valves including means operable to simultaneously close the inflow valve and open the outflow valve, the displacement of pressure fluid in said cylinder resulting from mold movement in the casting direction causing opening of said outflow valve and thereby controlling the velocity of movement of the mold inthe casting direction.

2. The combination as recited in claim 1 wherein said means for controlling operation of said valves comprises two. opposed springs acting upon said outflow valve, the resultant force of said springs determining the velocity of movement of the mold in the casting direction.

3. The combination as in claim 2, in which at least the resilient force of one of said springs is adjustable.

4. The combination as recited in claim 2 wherein said means for controlling operation of said valves cornprises means for forcibly closing said outflow valve during supply of pressure fluid to said cylinder to move said piston and mold in the direction opposite the casting direction.

5. The combination as recited in claim 4 wherein said means for controlling operation of said valves comprises a second, fluid pressure operated piston for opening said inflow valve to admit pressure fluid to said cylinder to actuate the first piston and mold in the direction opposite the casting direction.

6. The combination according to claim 5 wherein said means for forcibly closing said outflow valve comprises a third, fluid pressure operated piston.

7. The combination as recited in claim 6 wherein said means for controlling operation of said valves includes a pair of limit switches engageable by one of said mold and piston, electromagnetic controlled valve means actuated by said limit switches for controlling flow of pressure fluid to said second and third pistons.

8. The combination according to claim 5 wherein said inflow valve is provided with adjustable means to regulate its opening movement whereby to control the rate of supply of pressure fluid to said first cylinder and thereby the speed of the mold in the direction opposite the casting direction. 7

References Cited in the file of this patent UNITED STATES PATENTS 2,381,125 Herman Aug. 7, 1945 2,389,169 Stacy Nov. 20, 1945 2,997,741 Corssley Aug. 29, 1961 3,025,579 Littlewood Mar. 20, 1962 

1. IN COMBINATION, A MOLD OPEN AT OPPOSITE ENDS, AND MEANS FOR RECIPROCATING SAID MOLD IN THE CASTING DIRECTION WHEREIN THE MOVEMENT OF THE MOLD IN THE CASTING DIRECTION IS AUGMENTED BY THE FORCE OF AT LEAST A PART OF THE WEIGHT OF THE MOLD, SAID MEANS COMPRISING A FLUID PRESSURE CYLINDER, A PISTON RECIPROCABLE IN SAID CYLINDER AND SECURED TO SAID MOLD, A PRESSURE TO ONE PART OF SAID PRESSURE MEANS CONNECTING SAID RESERVOIR TO ONE PART OF SAID CYLINDER AT ONE SIDE OF SAID PISTON TO PERMIT FLOW OF PRESSURE FLUID INTO AND OUT OF SAID CYLINDER FOR MOVING SAID PISTON AND SECURED MOLD AGAINST AND IN THE DIRECTION OF CASTING RESPECTIVELY, AN INFLOW VALVE AND AN OUTFLOW VALVE CONTROLLING SAID FLOW OF PRESSURE FLUID INTO AND OUT OF SAID CYLINDER, AND MEANS FOR CONTROLLING OPERATION OF SAID VALVES INCLUDING MEANS OPERABLE TO SIMULTANEOUSLY CLOSE THE INFLOW VALVE AND OPEN THE OUTFLOW VALVE, THE DISPLACEMENT OF PRESSURE FLUID IN SAID CYLINDER RESULTING FROM MOLD MOVEMENT IN THE CASTING DIRECTION CAUSING OPENING OF SAID OUTFLOW VALVE AND THEREBY CONTROLLING THE VELOCITY OF MOVEMENT OF THE MOLD IN THE CASTING DIRECTION. 